18195840078 has 64 divisors (see below), whose sum is σ = 41528132352. Its totient is φ = 5265354240.

The previous prime is 18195840007. The next prime is 18195840079. The reversal of 18195840078 is 87004859181.

It is a happy number.

It is a super-2 number, since 2×18195840078² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a self number, because there is not a number n which added to its sum of digits gives 18195840078.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18195840079) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2025625 + ... + 2034587.

It is an arithmetic number, because the mean of its divisors is an integer number (648877068).

Almost surely, 2^18195840078 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18195840078, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20764066176).

18195840078 is an abundant number, since it is smaller than the sum of its proper divisors (23332292274).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18195840078 is a wasteful number, since it uses less digits than its factorization.

18195840078 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10529.

The product of its (nonzero) digits is 645120, while the sum is 51.

The spelling of 18195840078 in words is "eighteen billion, one hundred ninety-five million, eight hundred forty thousand, seventy-eight".